As the world pauses to remember the September 11 attacks on the United States, which killed some 3,000 people, the threat of another catastrophic act of terrorism seems all too plausible, both at home and abroad.

The watershed events of 9/11, aside from dragging the American people into a never-ending ‘War on Terror’, demonstrated how simple it is for a motley crew of terrorists to unleash pandemonium with the crudest weapons and methods. And with al-Qaeda’s deranged country cousins, Islamic State, now calling for lone wolf attacks against Western soft targets, the lesson is worth repeating.

On September 11, 2001, nineteen members of al-Qaeda - armed with nothing more sophisticated than box cutters and iron will - hijacked four US commercial aircraft and turned them into veritable cruise missiles. Two aircraft struck the North and South Towers of the World Trade Center in New York City, and a third hit the Pentagon complex in Washington, D.C. A fourth plane went down in a patch of forest in southwestern Pennsylvania after the passengers reportedly fought back against the hijackers.

The 19 al-Qaeda militants, whose leader Osama bin Laden was holed up in a cave in the Tora Bora mountain range of Afghanistan, certainly had no idea as to how successful their orchestrated attacks would be. With just two Boeing 767 aircraft they were able to bring down three Manhattan skyscrapers – the North and South Towers, as well as Building 7, a 47-storey building that collapsed in the evening of 9/11 after suffering office fires.

9/11 marked the first time in history that steel-framed high-rises collapsed due to fire.

Meanwhile, al-Qaeda militant Hani Hanjour, who had limited pilot training in the United States, was able to evade the most sophisticated air defense system in the world and crash American Airlines Flight 77 into the West wing of the Pentagon complex.

These incredible feats prove that our technologically dependent societies are very vulnerable to the most primitive methods of attack.

Could this happen again?

Admittedly, the 19 al-Qaeda terrorists had a lot of luck behind them on that September morning that changed our world forever.

First, the Bush administration didn’t seem overly worried about the prospects of a terrorist attack on US territory; their focus seemed more on what was happening in the Middle East. In fact, on August 6, 2001, President Bush receives a classified presidential daily briefing (PDB) that is entitled, “Bin Laden Determined to Strike in US,” which could not be any more direct than that with regards to the dangers America faced.

So how did Bush react to such startling information? According to Frank Rich of the New York Times, the president took the day off. “Reports at the time show that Mr. Bush broke off from work early and spent most of that day fishing,” Rich wrote.

The article went on to detail some other extraordinary lapses of judgment in the days preceding 9/11.

On Sept. 9, Pentagon chief Donald Rumsfeld “threatened a presidential veto if Congress moved $600 million out of the White House's prized ballistic missile defense system and into counterterrorism.” The next day, Sept. 10, Attorney General John Ashcroft “submitted a Justice Department budget request calling for increases in 68 programs, none of them directly related to combating terrorism.”

Although we would like to think that such glaring oversights could never happen today, it is already obvious that the US government is once again dropping its guard as far as preventing acts of terrorism is concerned.

Consider the Obama administration’s indifferent attitude to the porous US-Mexican border, a smoldering domestic issue that has taken center stage in the US presidential race. The weak US-Mexican border is an open invitation for any would-be terrorists to enter the country without government accountability. And it appears they are not refusing the invitation.

According to a military intelligence report, as cited by Judicial Watch, “Networks that specialize in smuggling individuals from regions of terrorist concern, mainly from the Afghanistan-Pakistan region, the Middle East, and East Africa, are indeed a concern…,” U.S. Southern Command (SOUTHCOM) Army Colonel, Lisa A. Garcia, was quoted as saying. “There are major hubs that serve as entry points into the region for migrants from those areas of concern attempting to enter the U.S. along our border with Mexico.”

The story gets better. Not only is it ridiculously easy for illegals to enter the United States, US taxpayers are then obliged to pay for them to be bussed to the city of their choice.

“The illegal immigrants who cross as incomplete family units simply enter the U.S. illegally…,” Breitbart reported. “U.S. taxpayers then fund bus tickets for the illegal immigrants to go to the U.S. city of their choosing.”

The terrorist threat facing the US and Europe is “bigger, wider and deeper” than at any point since the Sept. 11 attacks 15 years ago, according to US National Counterterrorism Center chief Nick Rasmussen, as quoted by The Washington Times.

The spread of Islamic State and its message presents a danger that is “considerably less predictable” than those posed by al Qaeda around the time of the 2001 attacks on the Pentagon and World Trade Center.

Despite such blatant disregard for national security at a time when talk of terrorism is rife, it is average Americans attempting to travel who are having their privacy - and private parts - invaded by overzealous TSA officers at airports.

Clearly, if ever there was another chance for terrorists to once again strike Americans on their home turf, an unprotected border is it.

Tragically, however, it seems the painful lessons of 9/11 have already been discarded, and as the saying goes, “those who fail to learn from history are doomed to repeat it.”